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An outdoor lighting manufacturing has
improved the appearance and functionality of their product by
producing CNC prototypes whose higher accuracy makes it possible to
refine their product to a higher degree. In the past, Architectural
Area Lighting (AAL) produced prototypes of their lighting fixtures
with hand tools but this was time-consuming and inaccuracies
hindered the design process. So the company purchased a CNC router
that produces prototypes from foam that match the computer aided
design (CAD) files used to define the part within a few thousands of
an inch. The CNC router typically takes only about 12 hours to
produce the prototype and runs by itself without requiring operator
attention. "Having an accurate prototype makes it possible to
evaluate the design to a higher degree and also lets us validate the
fit and functionality of the part," said Cory Landefeld, Product
Design Manager for AAL. "The new router paid for itself in less than
a year by drastically reducing the time and money we spent
prototyping."
Architectural Area Lighting is a leading
manufacturer of specification grade, outdoor contemporary and
traditional style lighting fixtures. The company specializes in
combining relevant aesthetic designs with superior lighting
performance to ensure the quality of light matches the quality of
the fixture. Some of the company’s typical lighting applications
include commercial buildings, retail applications, downtown street
lighting, educational facilities and sport complexes. AAL’s products
include period and contemporary lighting, floodlights, steplights,
wall sconces and bollards. The company design, develops and
fabricates their products while die castings are produced by
subcontractors.
The ability to design stunningly
attractive yet highly functional designs is the key to their
success. Using Ashlar’s Cobalt CAD software, designers have been
producing increasingly sophisticated 3D geometries that have
attracted the attention of architects, specifiers, engineers and
building owners. The designers typically conceive and tweak their
designs by viewing renderings on their computer screen. "But while
the latest computer modeling tools provide a very realistic view of
a proposed design, there are many important aspects of the design
that are difficult or impossible to evaluate on the screen," said
Robert Nankil, Product Designer for AAL. Rendering software is good
but it can’t perfectly represent the way that an object appears
under actual lighting conditions. We wouldn’t think of investing
tend of thousands of dollars to build die cast tooling until we were
able to review the actual part. |
We wouldn’t think of going into
production without being able to view a prototype under different
light conditions, put a bulb in the product to light it up, and
place it into a real-world setting so we can see how it looks.
Another reason that prototypes are needed is that many different
people in the company play a role in evaluating the design and some
are not experienced in the sometimes different art of translating
from the screen to the real world. There’s also the issue of
evaluating how the casting works with the different accessories and
making sure that everything fits together just right."
In the past, AAL technicians produced a
prototype of the design from foam using a lathe and hand tools. One
problem with this approach is that producing a complicated prototype
could easily tie up a skilled person for a week. And since the
company has switched to the Techno router, their designs have
continued to get more and more complex to the point that it would
take considerably longer, perhaps up to a month, to produce some of
them. Accuracy has always been a critical concern in producing the
prototypes because of thin wall thickness. But it was never possible
to achieve the desired level of accuracy with hand-built prototypes.
"The details just weren’t there which made it difficult to evaluate
the designs to the level that we would have liked," said Andy
McMillan, Product Designer. "Another problem was that the accuracy
wasn’t good enough to assemble the prototype with the accessories to
see how everything fit together and worked as an assembly. Because
of these problems, there were some cases where we had to make
expensive changes to the mold and other cases where we realized
after the product came out that we could have made improvements if
we had been able to view a more accurate prototype."
The design group jointly came to the
conclusion that a more accurate prototyping tool would help them
take their product development efforts to the next level. "We
considered several different options," Landefeld said. "Stereo
lithography had the accuracy we wanted but the machines that were
within our price range did not have the envelope that we needed,
which is 18 inches by 18 inches. We looked at some CNC machining
centers but the machines that were large enough for our parts were
very expensive, over $100,000 in most cases. Next, we looked at a
couple of CNC routers, machine tools with the flexibility and
accuracy of a machining center but which are designed for cutting
softer materials such as wood, plastics and foam. We quickly
discovered that these machines had the envelope that we need and
that the price was in an area that we could afford.
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Of the two that we considered, the
Techno machine was clearly superior in terms of the accuracy it
could provide. We also liked the fact that the Techno came as part
of a complete package that included all of the software that we
needed to get up and running. Finally, the price was right, under
$30,000 for the full package."
The Techno machine is constructed on
steel stress-relieved bases with hardened steel linear ways. Its
shaft-and-bearing system produces very smooth, play-free motion and
is an extremely rigid system that produces high-quality cuts. The
machine also uses anti-backlash ball screws. These screws have
excellent power transmission due to the rolling ball contact between
the nut and screws.
This type of contact ensures low
friction, low wear, and long life. The ball screws also make it
possible to produce wooden parts to the machine resolution of 0.0005
inch. Instead of being ball screw-driven, the less expensive
machines use rack and pinion gearing, which has too much play to
make accurate cuts in small areas. Also this type of gearing wears
out quickly in the dusty environment of a carpentry shop. The other
main difference we found between the Techno machine and the others
was that the Techno uses a servo motor to control cutting motion
while other machines use stepper motors, which can give a stair-step
cutting effect. With a smoother cut, sanding and finishing time is
kept to an absolute minimum.
With the new machine, AAL designers can
now produce prototypes that are as accurate as the finished parts
while occupying less than an hour of time on the part of the design
staff. The designers export the design from Cobalt in the IGES, STL
or DXF neutral file format. They then import the file into the
Visual Mill software provided with the Techno Router. With this
package, it is a relatively simple process to define the surfaces
that will be machined and generate tool paths. Normally, the part is
completed in two different setups, one machining the inside and the
other the outside of the part. Then the operator sets up the part,
starts the machine and is free to go back to their job until it is
ready for the second setup. The complicated fixtures produced by the
AAL typically take about 8 to 12 hours to machine.
When the part is done, the technician
removes it from the machine, performs some minor cleanup, paints it
and assembles it with other components that make up the complete
product, including a light bulb. |
